(a) Technical Field of the Invention
The present invention generally relates to electronic pacifier thermometers, and more specifically to an electronic pacifier thermometer in which its pacifier device has a built-in temperature sensor and in which its measurement device is structurally detachable so as to facilitate pacifier replacement, cleaning, and sterilization.
(b) Description of the Prior Art
Before the invention of the electronic thermometers, mercury thermometers are widely used in measuring human body temperature. The mercury thermometer relies on the simple principle that mercury changes its volume relative to its temperature. When measuring body temperatures, the mercury in the temperature-sensing probe expands and rises up the capillary in the glass tube of the thermometer. A user then can read the measurement result from the scale marked on or besides the glass tube of the thermometer. In recent years, as mercury is a highly contaminative material, electronic thermometers are developed and widely adopted to replace the mercury thermometers.
The principle behind electronic thermometers is as follows. A timing circuit built in an integrated circuit obtains a reference time interval within which a built-in RC oscillator generates a specific number of oscillation cycles based on an external reference resistor and an external reference capacitor. Then, the reference time interval is used to count the number of oscillation cycles generated by the RC oscillator based on an external thermistor (i.e., the temperature sensing element) and the same reference capacitor within the same reference time interval. A microprocessor then calculates a temperature value based on the measured oscillation cycles and presents the temperature value on a display.
More specifically, the integrated circuit has a pre-determined temperature value (usually 37° C. or 98.6° F.) and the thermistor is configured so that, at the predetermined temperature, the oscillation frequency based on the thermistor and the reference capacitor is identical to the oscillation frequency based on the reference resistor and the reference capacitor. Then, using the pre-determined temperature value as a basis, the difference between the two oscillation frequencies can be used to calculate the measured temperature. Since the two oscillation frequencies are based on the same reference capacitor, the resistance variation between the reference resistor and the thermistor at a specific temperature should be linearly corresponding to the temperature variation between the measured temperature and the pre-determined temperature so as to achieve accurate measurements. Conventionally, an electronic thermometer has the reference resistor and the thermistor fixedly installed on its temperature measurement circuit. The pairing of the reference resistor and the thermistor in the electronic thermometer is therefore not replaceable.
Electronic thermometers, due to their sturdiness, non-contamination, better measurement accuracy, and shorter measurement time, have gradually replaced the traditional mercury thermometers. In recent years, as they are constantly improved and enhanced as technologies advance, electronic thermometers have gained widespread popularity not only in ordinary households but also in public health facilities such as hospitals.
When using an electronic thermometer to measure a baby's body temperature, an accurate measurement is usually difficult as the baby is constantly moving. On the other hand, when the baby is sucking a pacifier, the baby is usually more emotionally stable and more susceptible to temperature measurement. Pacifier thermometers combining a pacifier and an electronic thermometer are therefore developed.
Conventional pacifier thermometers usually have the pacifier and the measurement device (including the temperature sensing element and the circuit board) integrated together and cannot be separated apart. As such, there are a number of disadvantages:
1. To protect the baby from various virus or bacterium infections, the pacifier is required to be washed and cleaned constantly. A pacifier thermometer often becomes defective from the wetness.
2. When the pacifier is damaged from the baby's constant sucking and biting, the entire pacifier thermometer has to be discarded even though the measurement device is perfectly functional.
3. As the pacifier and the measure device are integrated together, the measurement device is often damaged from the baby's sucking and biting. Again, the entire pacifier thermometer has to be discarded.
4. For sanitary reasons, public health facilities often reserve a pacifier thermometer for use by a single baby, which is not quite economical.
In addition, the display of some electronic thermometers does not have a backlight so that it is sometimes difficult to recognize the measurement result on the display. For some electronic thermometers, even though the display is equipped with a backlight, the backlight is lit only when the electronic thermometer reaches a stable reading and is turned off air a very short period of time, leaving no time for a user to pick up the electronic thermometer and recognize the measurement result.
Some electronic thermometers are equipped with a buzzer to deliver an alarming sound to remind a user when a stable reading is reached. However, the buzzer usually requires an enclosure structure and therefore takes quite a bit of space from the electronic thermometer.
Accordingly, after numerous improvement attempts and experiments, the present invention is provided herein to obviate the foregoing shortcomings and disadvantages of conventional electronic pacifier thermometers.